docs: def _interval_split(interval, only=None, context=None, event_re=re.compile("[A-Z][0-9]+")):
      """ Split C{interval} into a series of event type and timestamp tuples.
          An exaple of the input is "R1283008245P1283008268".
          Returns events in reversed order (latest first).
      """
      def split_event(event):
          "Helper to parse events."
          kind, val = event[:1], event[1:]
          try:
              return kind, float(val)
          except (TypeError, ValueError):
              return None, 0
  
      if hasattr(interval, "fetch"):
          interval = interval.fetch("custom_activations")
      ##import sys; print >>sys.stderr, "!!!!!isplit", interval, event_re.findall(interval)
  
      return list(reversed([split_event(i) for i in event_re.findall(interval) if not only or i.startswith(only)]))